I’m looking at some used crank sets on eBay and a couple include the BB. Is it ok to (re)use the BB they include or is it one of those items that should be considered disposable and replaced? If I should always use a new one then it will affect my purchasing decisions since an included BB doesn’t “sweeten the pot”.
I’ll need to change the BB no matter what since I’m going from a triple to a double.
An analogy comes to mind. I recently had the timing belt changed in my SUV. It’s recommended to replace the belt tensioner at the same time, even if it is still good.
BB are fine to reuse. There’s not reason not to use one if it’s still in good shape. Virtually the only issue is what state the bearings are in and that can be judged by hand. Plus, the penalty for misjudging is pretty small. Most BBs are ~$30. Figure a used one is worth half that. If you guess wrong (or the seller misstates the case) you’re not out a lot.
The reason for the tensioning belt pulley replacement (much like the water pump) is that you have to duplicate the work of replacing the belt to replace the pulley. Might as well get it all done at once so you don’t have to go back in there again. However, it’s not that big a deal to pull the cranks back off if the current BB doesn’t have a lot of life left in it but you still want to run it for a few months.
A more apt analogy to the tensioner pulley would be replacing your brake cables and housing when you re-wrap the bars. You’ve already got everything off and doing it again is a big pain.
Reuse it. I swap my cranks around with no problem as long as they have the same BB type.
IT is a modern BB. Right?
I don’t think that there should be any difference in the BB between a Double and a triple. The shaft on the a double vs. triple crank would be where the difference occurs. A GXP is a GXP the only differences taht you see are English thread vs. Italian. and you probably won’t see italian on a modern bike bought in the US.
For a full description of more than you ever wantef to know about bottom brackets, the immortal wisdom of Sheldon Brown, may he rest in peace, is where you want to go.
Bottom brackets are cheap. Use the one that comes with the crank and if it fails in a year just go buy another one.
The reason you want to replace the belt tensioner on your SUV at the same time as the timing belt is because the labor charges to pull off your radiator and fan are about 50X the cost of the stupid little tensioner so it’s insurance against having to go in at a later date and pay $300 in labor to replace a $6 part.
Thanks for the responses! They tell me what I needed to know.
Yea, my analogy wasn’t the best. It’s just what came to mind since I recently had this maintenance done to the Trooper. My thinking was to replace minor parts when performing major surgery. As I have never worked on cranks it is major to me.
No worries on the analogy. We were just trying to give you the proper one back to give you context.
Outboard bearing bottom brackets are a breeze to work on. I came up under three piece BBs and outboard bearings still feel like cheating to me. They’re so easy!